This invention relates to apparatus for controllably blending a continuous stream of small proportionate amount of a first liquid more acidic than natural ground water with a continuous stream of a pumped natural ground water carrier liquid in such a manner that when the pH, the measure of acidity or alkalinity, of the natural ground water is higher than what is desired for the proper agronomic requirements of the crop being irrigated then the blending rate of the first acidic liquid into the natural ground water carrier liquid can be precisely controlled so as to deliver the proper pH value of water to the irrigation system.
More particularly, the present invention relates to a golf course irrigation system using one or more pumps drawing water from a reservoir or well and pumping it through fixed and buried underground pipe lines to pop-up sprinkler heads or irrigation outlets. More particularly, the present invention relates to apparatus for controllably blending a relatively minute continuous stream of sulphuric acid of very low pH into a relatively large volume flowing water stream of a much greater pH; the pH value of 7 considered to be neutral pH water and said value of 7 pH water to be generally acceptable to the irrigation requirements of most turf grasses cultivated on golf courses.
Natural ground waters are almost always of a pH value higher than 7, the neutral point of alkalinity versus acidity. In areas of the West and Southwestern United States, the natural ground waters can be as alkaline as 8.4 pH; and, in these areas it is necessary to set up water treating systems to lower the water pH before it can be used because no turf grass does well in high pH water. A pH water value of 7 is neither acidic nor is it alkaline. In the professional practice of turf grass agronomy it is necessary that consideration be given to adjustments in soil reaction, or pH.
The preferred pH range for optimum turfgrass growth and vigor is 5.5 to 6.5 for the bentgrasses and fine-leafed fescues; 6.0 to 7.0 for bermudagrass. Kentucky bluegrass, and zoysiagrass; and 6.2 to 7.2 for annual bluegrass. It is therefore necessary that the pH of the irrigation water used to irrigate these grasses be taken into consideration for the health of the grass as well as the amendment of the soil pH. The pH value of the natural ground waters used for irrigation purposes is almost always higher than the neutral pH point of 7; that is, more alkaline, than is required for proper turf grass management.
In golf course irrigation systems, the requirement for turf irrigation water is typically supplied by a multiple pump station consisting of one or more synchronous speed electric motors driving turbine or centrifugal pumps and pumping through an automatic pressure reducing and pressure sustaining control valve such as those manufactured and supplied by CLA-VAL Co. of Newport Beach, Calif. This particular type of valve automatically performs two important functions. The first function maintains a constant downstream pressure regardless of fluctuating demand. The second function sustains the upstream pressure to a pre-determined minimum. Typically, the automatic control valve is a single seated, hydraulically-operated, pilot-controlled, diaphragm type globe valve.
The control system of the CLA-VAL{.TM.} consists of a reducing control sensitive to down-stream pressure changes, and pressure sustaining control that is sensed to the main valve inlet. The reducing control responds to slight downstream variations in pressure and immediately controls the main valve to maintain the desired downstream pressure. The pressure sustaining control is normally held open by the upstream pressure, but closes if this pressure drops to the control set point. This in turn closes the main valve to sustain the desired upstream pressure. The pressure sustaining and pressure reducing valve, hereinafter called CLA-VAL{.TM.} is adjustable to provide a constant downstream flowing line pressure regardless of the pumped inlet volume and pressure. A typical installation may provide a flowing line pressure immediately downstream of the CLA-VAL{.TM.} of 150 psi with the flowing line pressure immediately upstream of the CLA-VAL{.TM.} of 200 psi.
The various areas of the golf course to be irrigated typically may consist of separate irrigation zones such as fairways, tees, greens, and green banks which are irrigated separately from the rest of the course in a given irrigation cycle. The fairways consist of much larger areas of grass as compared to the tees or greens; therefore, it is necessary that a greater water volume be pumped to adequately irrigate these larger areas in a given time period. The CLA-VAL{.TM.} is used to provide a more or less constant operating pressure to the various sprinkler heads, and this pressure must be maintained at substantially that operating pressure recommended by the sprinkler manufacturer. These CLA-VALS{.TM.} have been used in this application for many years and their use and application is well known.